The Modulation of Chitosan-DNA Interaction by Concentration and pH in Solution

Dual-mode colorimetric and photothermal aptasensor for detection of kanamycin using flocculent platinum nanoparticles

Chitosan (CS)-stabilized platinum nanoparticles (CS/PtNPs) were employed to develop a novel aptamer-based dual-mode colorimetric and photothermal biosensor for selective detection of kanamycin (KAN). As a peroxidase-like catalyst, the CS/PtNPs showed outstanding catalytic activity for the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). As a stabilizing agent, CS excelled at fixing the KAN binding aptamer on the surface of the CS/PtNPs, amplifying their catalytic activity and enhancing colloidal dispersion and stability. The oxidized TMB (TMBox) functioned as a signal for the colorimetric, photothermal aptasensor because of its observable absorbance of light in the visible and near-infrared (NIR) regions. When light from a NIR laser was absorbed by the TMBox in the reaction solution, heat was generated in inverse proportion to the KAN concentration. The developed colorimetric and photothermal modes of the aptasensor showed a linear detection range of 0.1-50 and 0.5-50 μM, with a limit of detection (LOD) of 0.04 and 0.41 μM, respectively. Moreover, the aptasensor successfully determined KAN concentrations in spiked milk samples, verifying the reliability and reproducibility in practical applications. The dual-mode aptasensor based on CS/PtNPs for KAN detection, utilizing both color change and heat generation signals through a single probe (TMBox), demonstrates rapid response, simplicity in operation, cost-effectiveness, and high sensitivity. In addition, unlike typical immunoassays, this aptamer-based peroxidase-like nanozyme activation and inhibition strategy required no washing process, which was very effective in terms of reducing the time required for an assay and sustaining a high sensitivity.

Chitosan inhibits Penicillium expansum possibly by binding to DNA and triggering apoptosis

Chitosan is a natural polysaccharide that is abundant, biocompatible and exhibits effective antifungal activity against various pathogenic fungi. However, the potential intracellular targets of chitosan in pathogenic fungi and the way of activity of chitosan are far from well known. The present work demonstrated that chitosan could inhibit Penicillium expansum, the principal causal agent of postharvest blue mold decay on apple fruits, by binding to DNA and triggering apoptosis. UV-visible spectroscopy, fluorescence spectroscopy and electrophoretic mobility assay proved the interaction between chitosan and DNA, while atomic force microscope (AFM) observation revealed the binding morphology of chitosan to DNA. Chitosan could inhibit in vitro DNA replication, and cell cycle analysis employing flow cytometry demonstrated that cell cycle was retarded by chitosan treatment. Furthermore, the reactive oxygen species (ROS) assay and membrane potential analysis showed that apoptosis was induced in P. expansum cells after exposure to chitosan. In conclusion, our results confirmed that chitosan interacts with DNA and induces apoptosis. These findings are expected to provide a feasible theoretical basis and practical direction for the promoting and implementing of chitosan in plant protection and further illuminate the possible antifungal mechanisms of chitosan against fungal pathogens.

Photo-Cross-Linkable, Injectable, and Highly Adhesive GelMA-Glycol Chitosan Hydrogels for Cartilage Repair

Hydrogels provide a promising platform for cartilage repair and regeneration. Although hydrogels have shown some efficacy, they still have shortcomings including poor mechanical properties and suboptimal integration with surrounding cartilage. Herein, hydrogels that are injectable, cytocompatible, mechanically robust, and highly adhesive to cartilage are developed. This approach uses GelMA-glycol chitosan (GelMA-GC) that is crosslinkable with visible light and photoinitiators (lithium acylphosphinate and tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII(bpy)3 ]2+ and sodium persulfate (Ru/SPS)). Ru/SPS-cross-linked hydrogels have higher compressive and tensile modulus, and most prominently higher adhesive strength with cartilage, which also depends on inclusion of GC. Tensile and push-out tests of the Ru/SPS-cross-linked GelMA-GC hydrogels demonstrate adhesive strength of ≈100 and 46 kPa, respectively. Hydrogel precursor solutions behave in a Newtonian manner and are injectable. After injection in focal bovine cartilage defects and in situ cross-linking, this hydrogel system remains intact and integrated with cartilage following joint manipulation ex vivo. Cells remain viable (>85%) in the hydrogel system and further show tissue regeneration potential after three weeks of in vitro culture. These preliminary results provide further motivation for future research on bioadhesive hydrogels for cartilage repair and regeneration.

Chitosan polyplexes: Energetics of formation and conformational changes in DNA upon binding and release

Energetics of chitosan (CS) polyplexes and conformational stability of bound DNA were studied at pH 5.0 by ITC and HS-DSC, respectively. The CS-DNA binding isotherm was well approximated by the McGhee-von Hippel model suggesting the binding mechanism to be a cooperative attachment of interacting CS ligands to the DNA matrix. Melting thermograms of polyplexes revealed the transformation of different conformational forms of bound DNA in dependence on the CS/DNA weight ratio rw. At 0 Collapse

Key Words

• Chitosan−DNA interactions
• Conformational state of DNA in polyplexes
• Polyplex energetics
• Stability of polyplexes in near-physiological solvent conditions

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Affiliation(s)

Valerij Y Grinberg A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation; N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991, Russian Federation.
Tatiana V Burova A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation
Natalia V Grinberg A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation
Alexander S Dubovik A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation; N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991, Russian Federation
Vladimir E Tikhonov A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation
Alexander P Moskalets A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation
Victor N Orlov A.N. Belozerskij Institute of Physico-chemical Biology, M.V. Lomonosov Moscow State University, Vorobyevy Gory, 119334 Moscow, Russian Federation
Irina G Plashchina N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991, Russian Federation
Alexei R Khokhlov A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, Moscow 119991, Russian Federation; M.V. Lomonosov Moscow State University, Physics Department, Vorobyevy Gory, 119334 Moscow, Russian Federation

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Chitosan Particles Complexed with CA5-HIF-1α Plasmids Increase Angiogenesis and Improve Wound Healing

Wound therapies involving gene delivery to the skin have significant potential due to the advantage and ease of local treatment. However, choosing the appropriate vector to enable successful gene expression while also ensuring that the treatment's immediate material components are conducive to healing itself is critical. In this study, we utilized a particulate formulation of the polymer chitosan (chitosan particles, CPs) as a non-viral vector for the delivery of a plasmid encoding human CA5-HIF-1α, a degradation resistant form of HIF-1α, to enhance wound healing. We also compared the angiogenic potential of our treatment (HIF/CPs) to that of chitosan particles containing only the plasmid backbone (bb/CPs) and the chitosan particle vector alone (CPs). Our results indicate that chitosan particles exert angiogenic effects that are enhanced with the human CA5-HIF-1α-encoded plasmid. Moreover, HIF/CPs enhanced wound healing in diabetic db/db mice (p < 0.01), and healed tissue was found to contain a significantly increased number of blood vessels compared to bb/CPs (p < 0.01), CPs (p < 0.05) and no-treatment groups (p < 0.01). Thus, this study represents a method of gene delivery to the skin that utilizes an inherently pro-wound-healing polymer as a vector for plasmid DNA that has broad application for the expression of other therapeutic genes.

GelMA-glycol chitosan hydrogels for cartilage regeneration: The role of uniaxial mechanical stimulation in enhancing mechanical, adhesive, and biochemical properties

Untreated osteochondral defects are a leading cause of osteoarthritis, a condition that places a heavy burden on both patients and orthopedic surgeons. Although tissue engineering has shown promise for creating mechanically similar cartilage-like constructs, their integration with cartilage remains elusive. Therefore, a formulation of biodegradable, biocompatible biomaterial with sufficient mechanical and adhesive properties for cartilage repair is required. To accomplish this, we prepared biocompatible, photo-curable, mechanically robust, and highly adhesive GelMA-glycol chitosan (GelMA-GC) hydrogels. GelMA-GC hydrogels had a modulus of 283 kPa and provided a biocompatible environment (>70% viability of embedded chondrocytes) in long-term culture within a bovine cartilage ring. The adhesive strength of bovine chondrocyte-laden GelMA-GC hydrogel to bovine cartilage increased from 38 to 52 kPa over four weeks of culture. Moreover, intermittent uniaxial mechanical stimulation enhanced the adhesive strength to ∼60 kPa, indicating that the cartilage-hydrogel integration could remain secure and functional under dynamic loading conditions. Furthermore, gene expression data and immunofluorescence staining revealed the capacity of chondrocytes in GelMA-GC hydrogel to synthesize chondrogenic markers (COL2A1 and ACAN), suggesting the potential for tissue regeneration. The promising in vitro results of this work motivate further exploration of the potential of photo-curable GelMA-GC bioadhesive hydrogels for cartilage repair and regeneration.

Apta-sensor for selective determination of dopamine using chitosan-stabilized Prussian blue nanoparticles

Chitosan-stabilized Prussian blue nanoparticles (CS/PBNPs) were fabricated by a simple synthetic method and used to develop a novel aptamer-based colorimetric assay for selective determination of dopamine (DA). Scanning electron microscopy (SEM) images exhibited a uniform shape of the CS/PBNPs with an average diameter of 37.0 ± 3.2 nm. The CS/PBNPs exhibited strong peroxidase-like activity that catalyzed the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂). Chitosan was used for stabilization of the PBNPs and fixation of the DA aptamer on the surface of the CS/PBNPs. The catalytic mechanism of the CS/PBNPs was confirmed to involve first the decomposition of H₂O₂ into a hydroxyl radical (˙OH) and then oxidation of TMB by the ˙OH to produce a blue color. An aptamer-based colorimetric assay was made with the CS/PBNPs to detect DA at concentrations of 0.25-100 μM with a limit of detection (LOD) of 0.16 μM. For comparison, a gold nanoparticle (AuNP)-based apta-sensor detected DA in concentrations of 1-25 μM with a LOD of 0.55 μM. The recovery results of DA concentrations (0.25, 0.5, and 1 μM) from spiked human serum were 92.6%, 102.1%, and 103.9%, verifying the reliability and reproducibility of the CS/PBNP-based apta-sensor for determination of DA level in clinical applications. Moreover, compared to traditional immunoassay, this aptamer-based nanozyme activation/inhibition system needs no washing step, which is very useful to shorten the assay time and maintain high sensitivity.

Chitosan-Based Nanoparticles for Nucleic Acid Delivery: Technological Aspects, Applications, and Future Perspectives

Chitosan is a naturally occurring polymer derived from the deacetylation of chitin, which is an abundant carbohydrate found mainly in the shells of various marine and terrestrial (micro)organisms. Chitosan has been extensively used to construct nanoparticles (NPs), which are biocompatible, biodegradable, non-toxic, easy to prepare, and can function as effective drug delivery systems. Moreover, chitosan NPs have been employed in gene and vaccine delivery, as well as advanced cancer therapy, and they can also serve as new therapeutic tools against viral infections. In this review, we summarize the most recent developments in the field of chitosan-based NPs intended as nucleic acid delivery vehicles and gene therapy vectors. Special attention is given to the technological aspects of chitosan complexes for nucleic acid delivery.

General Characteristics, Biomedical and Dental Application, and Usage of Chitosan in the Treatment of Temporomandibular Joint Disorders: A Narrative Review

The aim of this narrative review was to present research investigating chitosan, including its general characteristics, properties, and medical and dental applications, and finally to present the current state of knowledge regarding the efficacy of chitosan in the treatment of temporomandibular disorders (TMDs) based on the literature. The PICO approach was used for the literature search strategy. The PubMed database was analyzed with the following keywords: (“chitosan”[MeSH Terms] OR “chitosan”[All Fields] OR “chitosans”[All Fields] OR “chitosan s”[All Fields] OR “chitosane”[All Fields]) AND (“temporomandibular joint”[MeSH Terms] OR (“tem-poromandibular”[All Fields] AND “joint”[All Fields]) OR “temporomandibular joint”[All Fields] OR (“temporomandibular”[All Fields] AND “joints”[All Fields]) OR “temporo-mandibular joints”[All Fields]). After screening 8 results, 5 studies were included in this review. Chitosan presents many biological properties and therefore it can be widely used in several branches of medicine and dentistry. Chitosan promotes wound healing, helps to control bleeding, and is used in wound dressings, such as sutures and artificial skin. Apart from its antibacterial property, chitosan has many other properties, such as antifungal, mucoadhesive, anti-inflammatory, analgesic, antioxidant, antihyperglycemic, and antitumoral properties. Further clinical studies assessing the efficacy of chitosan in the treatment of TMD are required. According to only one clinical study, chitosan was effective in the treatment of TMD; however, better clinical results were obtained with platelet-rich plasma.

The incipient denaturation mechanism of DNA

DNA denaturation is related to many important biological phenomena, such as its replication, transcription and the interaction with some specific proteins for single-stranded DNA. Dimethyl sulfoxide (DMSO) is a common chemical agent for DNA denaturation. In the present study, we investigate quantitatively the effects of different concentrations of DMSO on plasmid and linear DNA denaturation by atomic force microscopy (AFM) and UV spectrophotometry. We found that persistent length of DNA decreases significantly by adding a small amount of DMSO before ensemble DNA denaturation occurs; the persistence length of DNA in 3% DMSO solution decreases to 12 nm from about 50 nm without DMSO in solution. And local DNA denaturation occurs even at very low DMSO concentration (such as 0.1%), which can be directly observed in AFM imaging. Meanwhile, we observed the forming process of DNA contacts between different parts for plasmid DNA with increasing DMSO concentration. We suggest the initial mechanism of DNA denaturation as follows: DNA becomes more flexible due to the partial hydrogen bond braking in the presence of DMSO before local separation of the two complementary nucleotide chains.

The persistent length of DNA decreases significantly by adding small amount of DMSO. Local DNA denaturation occurs even at very low DMSO concentration, which can be observed by atomic force microscopy directly.

Limited-resource preparable chitosan magnetic particles for extracting amplification-ready nucleic acid from complex biofluids

Extraction and concentration of pure nucleic acid from complex biofluids are the prerequisite for nucleic acid amplification test (NAAT) applications in pathogen detection, biowarfare prevention, and genetic diseases. However, conventional spin-column mediated nucleic acid extraction is constricted by the requirement for costly power-intensive centralized lab infrastructure, making it unsuitable for limited-resource settings. Significant progress in lab-on-a-chip devices or cartridges (e.g., Cepheid GeneXpert®) that integrate nucleic acid extraction and amplification has been made, but these approaches either require additional equipment or are costly. Similarly, their complexities make them difficult to fabricate in low-resource settings by the end-user themselves. The application of magnetic particles such as silica-coated iron oxide beads for nucleic acid extraction is relatively instrument-free, rapid, user-friendly, and amenable to automation. But, they rely on hazardous chaotropic salt chemistry and ethanol desalting that could limit their efficacy for downstream NAATs. Recent advances in several types of novel material (e.g., polyamine) coated magnetic bead-based chaotropic salt-free extraction methods offer a possible solution to this problem. However, these materials also involve multistep synthesis impermissible in limited-resource settings. To offer a possible instrument-free magnetic particle-based nucleic acid extraction doable at limited-resource settings, we investigated the nucleic acid capture ability of two chitosan-coated magnetic particles that are preparable by minimally trained personnel using only a water bath and a magnetic stirrer within 6-8 h. We quantitatively probed the efficiency of the passive (without any electrical shaking or vortex-aided) DNA magnetocapture (i.e., binding to chitosan magnetic particles, physical separation from its sample of origin, and release from the particles) using UV₂₆₀. To explore their suitability towards clinically relevant sensitive downstream NAATs, 100-1000 copies (i.e., in the order of zeptomole) of Escherichia coli (E. coli) or human genomic DNA from aqueous solution, crude cell lysate, and fetal bovine serum were extracted by them and then successfully detected using quantitative real-time loop-mediated isothermal amplification (LAMP) or real-time polymerase chain reaction (PCR). Alongside, their suitability with gel-based LAMP, colorimetric LAMP, and in situ (on beads) LAMP was also probed. The required optimization of the amplification methods has been discussed. Overall, the turnaround time for the magnetocapture combined with NAAT was 1.5-2 h and is thus expected to aid in rapid clinical decision making. With the ease of preparation, reproducibility, and compatibility with downstream NAATs, we anticipate that these magnetic particles would facilitate the expansion and decentralization of nucleic acid-based diagnosis for limited-resource settings.

Nanocarrier-delivered small interfering RNA for chemoresistant ovarian cancer therapy

Ovarian cancer is the fifth leading cause of cancer-related death in women in the United States. Because success in early screening is limited, and most patients with advanced disease develop resistance to multiple treatment modalities, the overall prognosis of ovarian cancer is poor. Despite the revolutionary role of surgery and chemotherapy in curing ovarian cancer, recurrence remains a major challenge in treatment. Thus, improving our understanding of the pathogenesis of ovarian cancer is essential for developing more effective treatments. In this review, we analyze the underlying molecular mechanisms leading to chemotherapy resistance. We discuss the clinical benefits and potential challenges of using nanocarrier-delivered small interfering RNA to treat chemotherapy-resistant ovarian cancer. We aim to elicit collaborative studies on nanocarrier-delivered small interfering RNA to improve the long-term survival rate and quality of life of patients with ovarian cancer. This article is categorized under: RNA Methods > RNA Nanotechnology Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.

Polyelectrolyte-Based Platforms for the Delivery of Peptides and Proteins

The use of peptides and proteins in the pharmaceutical field has increased dramatically over recent years. They have been especially relevant to advances in the treatment of cancer, rheumatoid arthritis, leukemia, and cardiovascular, ophthalmological, metabolic, and infectious diseases. Despite the great potential of peptides and proteins, their use in pharmaceuticals has failed to reach its full potential because of some outstanding challenges. They are unstable under storage conditions and in biological milieus, and their high molecular weight limits permeation through biological membranes. A variety of delivery systems have been investigated to overcome these limitations. Polyelectrolytes (PEs) are molecules that bear multiple negative or positive charges. These molecules play an important role in various platforms relating to the delivery of peptide/protein-based drugs and subunit vaccines. The most commonly utilized PEs include chitosan, alginate, chondroitin sulfate, and poly(γ-glutamic acid). PE-based delivery systems, such as polyelectrolyte complexes (PECs), PE-coated nanocarriers, and PE multilayers, were designed to protect peptides and proteins from degradation and facilitate their absorption. These delivery systems are especially effective when administered orally or intranasally. This review emphasizes the important role of PEs and PE-based delivery vehicles in peptide/protein-based drugs and vaccines.